Sudoku is one of the most popular puzzle games in the world. It looks complicated at first, but the rules are actually very simple. You do not need math skills, calculators, or special knowledge. All you need is logic and patience.
In this guide, you'll learn how Sudoku works and how to solve your first puzzle.
What Is Sudoku?
A standard Sudoku puzzle contains a grid with 9 rows and 9 columns. The grid is divided into nine 3×3 boxes.
Some cells already contain numbers. Your goal is to fill the empty cells with numbers from 1 to 9.
The challenge is to place the numbers correctly according to three simple rules.
Sudoku Rules
Every number must follow these rules:
Rule 1: Each Row Must Contain 1-9
Every row must contain all numbers from 1 to 9 exactly once.
✅ Correct:
1 2 3 4 5 6 7 8 9
❌ Incorrect:
1 2 3 4 5 6 7 8 8
The number 8 appears twice.
Rule 2: Each Column Must Contain 1-9
Every column must contain all numbers from 1 to 9 exactly once.
A number cannot appear twice in the same column.
Rule 3: Each 3×3 Box Must Contain 1-9
Every 3×3 box must contain all numbers from 1 to 9 exactly once.
A number cannot appear twice inside the same box.
How to Find Missing Numbers
The basic Sudoku strategy is simple:
- Choose an empty cell.
- Look at its row.
- Look at its column.
- Look at its 3×3 box.
- Eliminate numbers that already exist.
- The remaining number is your answer.
Example
Suppose an empty cell is missing a value.
- The row already contains: 1, 2, 3, 4, 5, 6, 7, 8
- The only missing number is 9
The cell must contain 9.
This is the easiest type of Sudoku move.
Start With Easy Areas
Many beginners make the mistake of scanning the entire puzzle.
Instead:
- Look for rows with only one or two empty cells.
- Look for columns that are nearly complete.
- Look for 3×3 boxes with many numbers already filled.
These areas are usually the easiest to solve.
Use the Process of Elimination
Sometimes several numbers are possible.
For example:
A cell cannot contain:
- 1
- 2
- 3
- 5
- 7
- 8
The only remaining candidates are:
- 4
- 6
- 9
You may not know the answer immediately, but you've narrowed the possibilities.
As you solve more cells, the correct number will become obvious.
Pencil Marks
Many Sudoku players write small candidate numbers inside empty cells.
These are called pencil marks.
For example:
2 5 8
This means the cell could be 2, 5, or 8.
As you gather more information, you remove impossible candidates until only one remains.
Pencil marks are especially useful in medium and hard puzzles.
Common Beginner Mistakes
Guessing Too Early
Sudoku is a logic puzzle.
If you're stuck, keep looking for clues instead of guessing.
Random guesses often create mistakes that make the puzzle impossible later.
Forgetting to Check the Box
Many beginners check only the row and column.
Always check the 3×3 box as well.
A number may be missing from the row but still be blocked by the box.
Moving Too Fast
A single wrong number can cause problems throughout the puzzle.
Take a few extra seconds to verify each move.
Beginner Sudoku Strategy
When solving a puzzle, follow this routine:
- Scan all rows for easy numbers.
- Scan all columns.
- Scan all 3×3 boxes.
- Fill any obvious cells.
- Add pencil marks if needed.
- Repeat the process.
Most easy Sudoku puzzles can be solved using this method alone.
Do You Need Math Skills?
No.
Sudoku uses numbers, but there is no arithmetic involved.
You never add, subtract, multiply, or divide.
The numbers are simply symbols that must be arranged according to the rules.
You could replace the numbers with letters and the puzzle would work exactly the same way.
Tips for Your First Sudoku Puzzle
- Start with an easy puzzle.
- Look for rows and columns with many numbers already filled.
- Use pencil marks when necessary.
- Check all three Sudoku rules before placing a number.
- Stay patient and avoid guessing.
The more puzzles you solve, the faster you'll recognize patterns and find missing numbers.
Final Thoughts
Sudoku may look intimidating at first, but the rules are surprisingly simple. Every puzzle is solved using logic, observation, and elimination.
Start with easy puzzles, focus on one area at a time, and remember the three core rules:
- No repeated numbers in a row.
- No repeated numbers in a column.
- No repeated numbers in a 3×3 box.
With a little practice, you'll be solving Sudoku puzzles confidently and enjoying one of the world's most popular logic games.
What's Next?
Once you're comfortable with the basics, learn the two foundational solving techniques:
- Naked Single — when a cell has only one candidate left
- Hidden Single — when a number can only go in one place within a unit
These two techniques alone can solve most Easy-level puzzles.